This invention is related to a mechanical vibrating drive system for a vibratory conveyor apparatus and, more particularly, to a vibratory conveyor apparatus utilizing a set of eccentric rotating weights to impart a resultant vibratory drive force to the conveyor apparatus.
Eccentric weight drive systems for providing linear force generation to vibratory conveyor apparatus are known per se. The systems typically operate to change either the direction or the magnitude of a force applied to a trough mounted to a stationary support through a plurality of elastic members such as springs. The systems utilize a plurality of rotating shafts and associated eccentric weights to supply a cyclical force to the vibratory trough. A mechanism in the system is used to adjust the relative positioning of one or more of the rotating shafts carrying the eccentric weights. Varying the relative positioning of the rotating shafts and eccentric weights varies the direction of the maximum throw to the trough of the conveyor.
An example of a system utilizing fixed eccentric rotating weights for changing the force direction is described in detail in U.S. Pat. No. 5,064,053 assigned to the same assignee as the present invention. In the system of the '053 patent, a single rotating shaft bearing an eccentric weight is in a parallel relationship with and positioned between paired additional rotating shafts bearing eccentric weights. The centered single shaft rotates in one direction while the paired shafts rotate in the opposite direction but at the same number of revolutions per minute. In any 360.degree. rotation of the shafts, all eccentric weights will be oriented so that the centrifugal forces, due to rotation of the eccentric weights, will be in the same direction, i.e., at the same angle with respect to the horizontal plane twice in the rotation. This provides a maximum resultant force, the aggregate centrifugal force, each time in that direction. Similarly, a minimum resultant force will be experienced twice in a 360.degree. rotation. By varying the orientation of the single shaft with respect to the paired shafts, the "phase angle" relationship between the single rotating shaft and the paired rotating shafts, can be changed, thus changing the direction of "angle of attack" of the maximum resultant force supplied to the trough.
When a vibratory conveyor apparatus is used to transfer product, there is frequently the need to reverse the flow of the product being conveyed. While electronic drive capabilities such as described in U.S. Pat. No. 5,615,763 assigned to the same assignee as the present invention allow for a rapid change of direction of flow of the product, such systems are expensive. It would be far more desirable in many applications of moving product to use a mechanical system in which the shafts of the conveyor are driven by a common drive to change the product flow direction. However, to reverse the flow in such mechanical systems requires considerable down time of the system as it is necessary to physically change the positioning of one or more of the eccentric weights so that the resultant force is directed in the opposite quadrants. This becomes a labor intensive and costly procedure that is highly undesirable when the vibratory apparatus is a critical part of the process. Thus, there is a paramount need for a mechanical vibrating drive system that will allow the user to easily change the direction of flow of the conveyed product without incurring the down time of the system heretofore necessary with prior art mechanical vibrating drive systems.